1. Field of the Invention
The present invention relates to a contact of a vacuum interrupter, and more particularly, a contact of a vacuum interrupter capable of improving arc-extinguishing and insulating capabilities between contacts.
2. Background of the Invention
A vacuum interrupter is an electric power device, which is generally used as a core component of a vacuum circuit breaker or a switchgear for opening and closing a high voltage or super high voltage electric power circuit. The vacuum interrupter is provided with contacts within a vacuum container and can open and close a high voltage circuit over 1000 volts or a super high voltage circuit of tens of thousands of volts with an excellent arc-extinguishing performance.
Hereinafter, a general configuration and an operation of the vacuum interrupter will be described with reference to FIG. 1.
In general, the vacuum interrupter, as illustrated in FIG. 1, includes an insulating container 9, a movable electrode 1, a movable contact 2, a fixed electrode 4, a fixed contact 3, a fixed-side seal cup 8, a movable-side seal cup 7, a bellows tube 5, a bellows tube shield 6, and a center shield 10.
The insulating container 9 refers to a container for receiving therein the components of the vacuum interrupter. The insulating container 9 may be made of ceramic which is an electric insulating material, and formed in a cylindrical shape that both ends in a lengthwise direction are open.
The movable electrode 1 may be implemented as a conductive electrode, which is connected to a driving force transfer member, such as a rod, a lever or a link (not shown), and linearly movable by a driving force transferred from a driving power source, such as a motor or a spring (not shown) through the driving force transfer member.
The movable electrode 1 may be electrically connected to a load side of an electric power circuit, for example.
The movable contact 2 refers to a contact which is attached to one surface of the movable electrode 1 facing the fixed electrode 4 so as to be linearly movable together with the movable electrode 1. The movable contact 2 is made of a metal having characteristics, such as conductivity, resistance to fusion, current breaking, and high voltage withstand capability.
The fixed electrode 4 refers to an electrode which is located at a fixed position, and may be disposed to face the movable electrode 1. The fixed electrode 4 may be electrically connected to a power source side of the electric power circuit, for example.
The fixed contact 3 refers to a contact which is attached to one surface of the fixed electrode 4 facing the movable electrode 1 and fixed together with the fixed electrode 4. The fixed contact 3 is made of a metal having characteristics, such as conductivity, resistance to fusion, current breaking, and high voltage withstand capability.
The fixed-side seal cup 8 refers to a member in the shape of a cup with a low height so as to air-tightly close one of the openings at both ends of the ceramic insulating container 9, namely, one opening at which the fixed electrode 4 is disposed. The fixed-side seal cup 8 may be provided with a through hole formed through a center thereof such that the fixed electrode 4 is inserted therethrough.
The fixed-side seal cup 8 may be air-tightly welded on the ceramic insulating container 9 and the fixed electrode 4.
The movable-side seal cup 7 refers to a member in the shape of a cup with a low height so as to air-tightly close one of the openings at both ends of the ceramic insulating container 9, namely, one opening at which the movable electrode 1 is disposed. The fixed-side seal cup 8 may be provided with a through hole formed through a center thereof such that the movable electrode 1 is inserted therethrough.
The movable-side seal cup 7 may be air-tightly welded on the ceramic insulating container 9 and the bellows tube 5.
The bellows tube 5 is implemented as a metal tube which has a hollow inside such that the movable electrode 1 is inserted therethrough, and has a plurality of folds with flexibility so as to allow the movement of the movable electrode 1.
One end portion of the bellows tube 5 may be welded on the movable-side seal cup 7, and another end portion thereof may be welded on the bellows tube shield 6.
The bellows tube shield 6 is implemented as a metal member in the shape of a cup which surrounds the bellows tube 5 to protect the bellows tube 5 from arc, which is generated when the movable contact 2 is separated from the fixed contact 3, and metal vapors generated by the arc.
A penetrating portion formed at the center of the bellows pipe shield 6 may be welded on a flange which protrudes from an outer circumferential surface of the movable electrode 1, such that the bellows tube shield 6 can be linearly moved together with the movable electrode 1. Simultaneously, the another end portion of the bellows tube 5 can also be linearly moved together.
The center shield 10 may be supported by a shield supporting shaft 11 which is inserted into the ceramic insulating container 9, and also protect an inner wall of the ceramic insulating container 9 from the arc and the metal vapors.
Hereinafter, an operation of opening and closing an electric power circuit of the thusly-configured vacuum interrupter will be briefly described with reference to FIG. 1.
First, the operation of closing the electric power circuit will be described.
When the movable electrode 1 illustrated in FIG. 1 is moved up by a driving force which is generated from a driving power source such as the motor or the spring (not shown) and transferred through a driving force transfer member such as the rod, the lever or the link (not shown), the movable contact 2 attached to the movable electrode 1 is brought into contact with the corresponding fixed contact 3 of the fixed electrode 4. Accordingly, the load side connected with the movable electrode 1 and the power source side connected with the fixed electrode 4 are connected to each other. Consequently, the electric power circuit is closed and thus current flows from the power source side to the load side.
Next, the operation of opening the electric power circuit will be described.
When the movable electrode 1 illustrated in FIG. 1 is moved down by a driving force which is generated from a driving power source such as the motor or the spring (not shown) and transferred through a driving force transfer member such as the rod, the lever or the link (not shown), the movable contact 2 attached to the movable electrode 1 is separated from the corresponding fixed contact 3 of the fixed electrode 4. Accordingly, the load side connected with the movable electrode 1 and the power source side connected with the fixed electrode 4 are separated from each other. Consequently, the electric power circuit is open and thus current flowing from the power source side to the load side is broken.
Hereinafter, the contacts (movable contact and fixed contact) of the related art vacuum interrupter will be briefly described with reference to FIGS. 2 and 3.
Referring to FIG. 2, the contacts of the related art vacuum interrupter are so-called spiral contacts, and include the movable contact 2 and the fixed contact 3, as aforementioned. The movable contact 2 and the fixed contact 3 are supported by the movable electrode 1 and the fixed electrode 4, respectively.
Here, the movable contact 2 and the fixed contact 3 have the same structure.
The movable contact 2 may be provided with a plurality of cut portions 2c which are spirally formed from a center thereof toward an outer side in a radial direction. By the formation of the cut portions 2c, a plurality of spiral petal portions 2b are formed between the cut portions 2c. 
Similarly, the fixed contact 3 may be provided with a plurality of cut portions 3c which are spirally formed from a center thereof toward an outer side in a radial direction. By the formation of the cut portions 3c, a plurality of spiral petal portions 3b are formed between the cut portions 3c. 
The movable contact 2 and the fixed contact 3 in the spiral shape are separated from each other upon an opening operation, and accordingly arc is generated between the movable contact 2 and the fixed contact 3.
In this instance, the arc is rotated along the spiral petal portions 2b and 3b by a force, which is generated by interaction between an arc current flowing along the arc electrically connecting the movable contact 2 and the fixed contact 3 and a radial magnetic field generated by the arc current. Accordingly, the arc is evenly extinguished on surfaces of the movable contact 2 and the fixed contact 3.
Meanwhile, to improve an insulating property between the movable contact 2 and the fixed contact 3, as illustrated in FIG. 2, inclined portions S are formed at edge portions of the fixed contact 3 and the movable contact 2, on which an electric field is concentrated at the maximum.
The inclined portions S can increase a distance between the edges of the fixed contact 3 and the movable contact 2 on which the electric field has been concentrated at the maximum. This may result in reducing the electric field between the fixed contact 3 and the movable contact 2, and accordingly improving the insulating property between the fixed contact 3 and the movable contact 2.
However, in case where the inclined portions S have an inclination angle greater than a predetermined angle, an arc driving force involved in arc interruption is lowered, which may cause a number of arc interruption and a success rate of arc interruption to be reduced and lowered, thereby lowering arc extinguishing efficiency.
Meanwhile, in Korean Registration Patent No. 10-1085286 (Nov. 14, 2011) as a prior art of the present invention, ‘Contact of Vacuum Interrupter’ is disclosed.